1. Field of the Invention
The present invention relates to techniques for characterizing the pulse profile of a fast x-ray source, and more specifically, it relates to a pump-probe technique for measuring the rise time of a fast x-ray pulse.
2. Description of Related Art
Conventional high speed x-ray diagnostics (e.g., x-ray streak cameras, PIN diodes, diamond PCD devices) do not provide sufficient time resolution in order to resolve x-ray pulses having a duration that is less than about 1 ps. For optimization and study of ultrafast systems in general, it is important to have this capability developed.
Measurements of very short-duration x-ray pulses have been made using very fast photodetectors, which can resolve events as short as 50 ps, and with x-ray streak cameras which can resolve events as short as 1 ps. A typical x-ray streak camera provides a continuous exposure for a very short time interval and achieves good time resolution by rapidly changing the position, or streaking, the image on the recording surface, which may be film or a phosphor screen. The image is rapidly moved over the recording surface by using either a rapidly rotating mirror or deflection plates. X-ray streak cameras have been previously used for measurement of light or x-ray fluxes of relatively large magnitude. For x-ray measurements of large flux magnitude, the x-rays are collimated through a small slit. It is desirable to provide a pump-probe solution to measuring events where detector resolution is insufficient to resolve the event. The present invention provide such techniques.